Mark Drakeford has been urged to U-turn on the new 20mph speed limit in Wales.
Earlier this month, Wales became the first country in the UK to drop the default speed limit from 30mph to 20mph for residential roads.
A record-breaking petition against the move by the Labour-run Welsh Government has now surpassed 443,000 names.
Speaking to the Express at the Conservative Party conference, Welsh Tory leader Andrew RT Davies called on the First Minister to “think again”.
He said: “This is a stupid move on the government’s behalf, they need to change direction, they need to listen to those 450,000 signatures and actually bring in measures around schools, hospitals and care homes where 20mph would be sensible.
“But the blanket 20mph across the whole of the country is economically damaging.”
Mr Davies said the 20mph speed limit is having a “massive impact” on Wales.
He said: “We know for a fact from the government’s own figures it’s going to cost the Welsh economy up to £9billion.
“We know the emergency services have said they’re going to have slower response times. And we’ve got a massive petition, a public outcry about it, over 450,000 people have signed the petition against it.
“So that’s the impact it’s having and it’s only two weeks in.”
The Welsh Government has said that cutting the speed limit would protect lives and save the NHS in Wales £92million a year.
But the project is costing around £33million to implement, while it is expected to hit the economy by up to £9billion.
Not all 30mph roads will see their speed limits reduced as councils have the power to exempt certain roads from the scheme.
Mr Davies also warned more parts of the UK could be hit by more 20mph zones if Labour leader Sir Keir Starmer takes power at the next general election.
Sir Keir has previously described the Welsh Government as providing a “blueprint for what Labour can do across the UK”.
Mr Davies said: “If people at the next general election vote Labour they’ll get what Mark Drakeford’s delivering in Wales across the rest of the UK which is 20mph, massive NHS waiting times, an economy that isn’t firing on all cylinders and sadly job numbers that aren’t moving in the right direction.
“So let’s not make that happen, let’s us Conservatives roll our sleeves up, go out there, take the fight to Labour and highlight what Mark Drakeford is doing in Wales and Keir Starmer could potentially do around the rest of the UK. It would be the breakup of the UK as we know it.”
The petition against the 20mph speed limit on the Senedd website has gathered 456,000 signatures so far.
More people have backed the petition than voted for Mr Drakeford’s party at the Welsh Parliament elections in 2021.
A Welsh Government spokesperson said: “Mr Davies is fully aware that this is not a blanket restriction and is it profoundly disappointing that he is continuing to mislead people over the introduction of 20mph.
“Speed limits on a great number of roads in Wales are unchanged and journey times take around a minute longer. This will save lives and make our communities safer.”
